Coupon field in cart widget

I need to modify the ‘mini-cart.php’ file. I did it like /enfold-child/woocommerce/cart/mini-cart.php.
If I make any changes in it there aren’t any changes on the front-end. How is this possible?

Hi,

I added the coupon field to my mini-cart.php in my child theme. Found out that I needed to erase my browse data to see the changes.
You can find the page in private content of my first question. You can add a product to your cart and use the coupon I mentioned in the private content to see how the flow is right now.

I added this to my mini-cart.php code:

<form class="checkout_coupon woocommerce-form-coupon" method="post">
        <p style="color:white;"><?php esc_html_e( 'Kortingscode', 'woocommerce' ); ?></p>
        <p class="form-row form-row-first">
            <input type="text" name="coupon_code" class="input-text" placeholder="<?php esc_attr_e( 'Coupon code', 'woocommerce' ); ?>" id="coupon_code" value="" />
        </p>
        <p class="form-row form-row-last">
            <button type="submit" class="button" name="apply_coupon" value="<?php esc_attr_e( 'Apply coupon', 'woocommerce' ); ?>"><?php esc_html_e( 'Apply coupon', 'woocommerce' ); ?></button>
        </p>
        <div class="clear"></div>
    </form>

Normally if you add the coupon in the cart page and remove it. It happens with AJAX and does not reload the page. Can I achieve this here too because now it reloads the page :(